Field of the Invention
Embodiments of the invention generally relate to a permanently or temporarily implantable medical device with an elongate electrical conductor, and a production method for an implantable medical device.
Description of the Related Art
Generally, medical devices containing electrical conductors, for example electrode lines for electro-stimulation or electrodes for cardiac pacemakers, have a disadvantage that the electrical conductor may heat up in an electromagnetic alternating field, for example in an MRI scanner, since electromagnetic alternating fields typically induce electrical currents in the electrical conductor. Typically, the heating occurs at ends of electrode lines and is dependent on the amplitude of the waves of the electromagnetic alternating fields, wherein the heating is generally greatest with formation of standing waves.
Implantable cardiac pacemakers or defibrillators are typically connected to at least one stimulation electrode line. A distal end of a stimulation electrode line, which is typically placed in a heart, generally includes one or more electrode poles. Such electrode poles, generally, are used to deliver electrical pulses, for example to the heart tissue (myocardium), or to sense electrical fields in order to sense activity, for example cardiac activity, from the heart tissue, within the scope of what is known as “sensing”.
Generally, two electrode poles typically form electrically conductive surface portions of an electrode line. The electrode poles are typically provided as ring electrodes in the form of a ring around the electrode line or in the form of a point electrode or tip electrode at the distal end of the electrode line. The electrode poles are generally electrically conductively connected, via one or more electrical conductors, to contacts of an electrical terminal of the electrode line at the proximal ends thereof. Typically, the electrical conductors may be used for transmission of stimulation pulses to the electrode poles and/or for transmission of electrical signals, received by the electrode poles, to the proximal end of the electrode line. Generally, electrical conductors of the electrode line (that is to say the primary function of the electrode line) are referred to within the scope of this text as functional conductors.
Typically, via external alternating magnetic fields, electrical currents may be induced into the functional conductors, and for example may lead to heating of the functional conductors and/or of the electrode poles connected thereto. If the functional conductors are connected to electrode poles, which may have contact with surrounding tissue during operation, the induction of currents in a functional conductor may generally lead to heating of the electrode poles connected to the functional conductors and to heating of the surrounding tissue.
U.S. Pat. No. 7,904,178 to Williams et al., entitled “Medical Electrical Lead Body Designs Incorporating Energy Dissipating Shunt”, discloses an elongate body of a medical electrical lead including at least one conductor formed into a coil. According to Williams et al., the conductor includes a first portion extending within an outer insulation sleeve, and a second portion, which extends outside the outer insulation sleeve, used as an energy-diverting shunt.
U.S. Pat. No. 6,871,091 to Wilkinson et al., entitled “Apparatus and Method for Shunting Induced Currents In An Electrical Lead”, discloses an electrical lead with an elongate body. According to Wilkinson et al., the electrical lead includes distal and proximal end portions, a first electrode connected to the distal end portion of the elongate body and a first conductor extending between the distal and proximal end portions, wherein the conductor is electrically connected to the first electrode. The system of Wilkinson et al. also includes a second electrode connected to the elongate body, and a capacitor electrically connected to the first conductor and the second electrode.